Alkaloid profiling of the traditional Chinese medicine Rhizoma corydalis using high performance liquid chromatography-tandem quadrupole time-of-flight mass spectrometry

Abstract

Since alkaloids are the major active constituents of Rhizoma corydalis (RC), a convenient and accurate analytical method is needed for their identification and characterization. Here we report a method to profile the alkaloids in RC based on liquid chromatography-tandem quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS/MS). A total of 16 alkaloids belonging to four different classes were identified by comparison with authentic standards. The fragmentation pathway of each class of alkaloid was clarified and their differences were elucidated. Furthermore, based on an analysis of fragmentation pathways and alkaloid profiling, a rapid and accurate method for the identification of unknown alkaloids in RC is proposed. The method could also be useful for the quality control of RC.

Keywords: Alkaloid; Fragmentation pathway; LC–Q-TOF-MS/MS; Rhizoma corydalis.

Graphical abstract

Figure 1

Chemical structures of the four types of alkaloids in RC.

Figure 2

Base peak currents (BPC) of the solution of standards (A) and extract of RC (B). Peak identities: 1, Tetrahydrocolumbamine; 2, Tetrahydrojatrorrhizine; 3, Protopine; 4, Allocryptopine; 5, Demethyleneberberine; 6, Tetrahydropalmatine; 7, Coptisine; 8, Glaucine; 9, Canadine; 10, Corydaline; 11, Columbamine; 12, Jatrorrhizine; 13, Worenine; 14, Berberine; 15, Palmatine; 16, Dehydrocorydaline.

Figure 3

MS/MS spectrum and fragmentation of tetrahydropalmatine.

Figure 4

MS/MS spectrum and fragmentation of corydaline.

Figure 5

MS/MS spectrum and fragmentation pathway of protopine.

Figure 6

MS/MS spectrum and fragmentation pathway of berberine.

Figure 7

MS/MS spectrum (A) and fragmentation pathway (B) of Coptisine.

Figure 8

MS/MS spectrum and fragmentation pathway of Glaucine.

Figure 9

MS/MS spectrum and fragmentation pathway of unknown alkaloids X1 (A) and X2 (B).